The invention relates to a method for the production of paste products having a formed gluten framework, in which at least one powdery dough base like flour, dust, semolina or a mixture consisting essentially of these is mixed as a dry component with a liquid component, the dough mass being formed therefrom is kneaded by means of an extruder and a finished dough is formed into past products, wherein the temperature of the dough mass for the formation of the gluten framework is kept below 50xc2x0 C. during carrying out of the method and to a device for the production of paste products, in particular for carrying out of the method according to any of the claims, having an extruder, at the outlet of which prepared dough can be transformed under pressure into a desired form of the past product.
EP 351 423 B1 describes a method according to the preamble for the production of dough for farinaceous pastes, in which a dry ground or milled product such as flour or the like is moistened with water in a premixer, so that the flour is brought into a moist, friable, loose state. This friable material is supplied by means of a hopper or downpipe to a feed screw of a kneading machine. The dough is then formed in a continuous process in an extruder-like apparatus and from there it is transferred into a following mechanism for pressing and molding.
The supply of the flour in the moist, friable and sticky state is unsatisfactory as a result of possible adhesion in the feed hopper and due to hygienic disadvantages. In addition, the necessary transfer of the dough following the continuous dough production process into a following pressing and molding means is unsatisfactory from the standpoint of a continuous process operation.
FR-A-2 618 643 discloses an apparatus according to the preamble used for the production of baked dough. A mixture of flour, salt and sugar as well as fat is introduced by means of the opening into an extruder having two shafts rotating in the same direction. Introduction takes place by means of a further opening of a liquid phase consisting of flour, salt, sugar, water and fat into an extruder zone A. Following a first mixing in extruder zones A and B the dough is heated to 90 to 110xc2x0. In the following sections D and E cooling takes place to approximately 60xc2x0 C., followed by a further supply of a mixture of flour, water, fat, etc, by means of a third opening. The dough is extruded following a further cooling.
U.S. Pat. No. 4,948,612 describes an apparatus for the production of a biscuit or cookie-like product. By means of a first supply device sugar is introduced into a double extruder with two shafts rotating in the same direction. As a result of compressive and shear forces in the extruder the sugar is melted and a temperature of 90 to 135xc2x0 C. is reached. Water is then fed in by means of a pipe, whilst flour is introduced into the extruder by means of a second supply device. Until it is discharged from the extruder, said mass is to be kept at a temperature of 90 to 135xc2x0 C.
These devices are not, or at best only suitable to a limited extent for the production of dough, which is in particular very sensitive to high temperatures, accompanied by the formation of a gluten framework.
The object of the invention is therefore to provide a paste or dough production method and device making it possible to produce dough products with a gluten framework in a simple and efficient manner.
According to the invention, this object is achieved by a particular method.
In this procedure a milled product-such as flour, dust or semolina is fed in or supplied to the extruder in dry form so that, compared with the supply of the already moistened flour, which then forms crumbs or lumps, there is a simpler dosing or metering under hygienically improved conditions as a result of a lack of moisture or wetness in the feed. The feeding or dosing in can therefore take place with a high dosing precision and in a more compact feed unit, the cleaning thereof being simplified. The method can be performed with a milled product constituted by cereals and in particular with milled wheat products of the gluten-rich hard wheat type. However, it is also suitable for milled products from legumes such as soya beans, if gluten framework constituents are present or are added in an adequate quantity. However, it is also possible to supply several dry components or mixtures thereof, which e.g. include vegetable powders or egg powder.
The liquid is fed into the dry components or the milled product or fluor on its feed path into the kneading zone. The flour is then rapidly and uniformly moistened with the inflowing or injected liquid component, which is normally water, so that subsequently the dough mass consisting of flour and water can be kneaded. It is also possible to feed in other or additional liquid components, such as liquid egg, dissolved vegetable powders, etc.
By counter-rotating the extruder shafts an excellent kneading effect is achieved. Although the counter-rotation of the extruder shafts results in high shear forces, a respective generation of friction heat is avoided by working in a defined air volume. This air volume reduces the friction in the dough and provides a heat buffer avoiding a super heating of the heat-sensitive gluten framework.
In the proposed method a clearly defined air volume is worked into the dough mass by operating the extruder at below its feed capacity. Less milled product is fed into the conveyor screw zone than the said screw could discharge, i.e. the possible discharge capacity of the screw is greater than the flour infeed. This operating mode can be achieved in conjunction with a controlled flour metering and flour infeed and a speed regulation of the extruder screws. By working air into the dough mass it is possible to produce more loose dough or paste products such as home-made noodles, which are also beneficial to persons having to follow a diet. This is particularly advantageous for the production of instant noodles and the time for blanching, oiling or frying can be reduced or these procesces can be omitted. For a clearly defined setting of the air proportion, which can also be virtually zero, the complete preparation and processing of the dough in an extruder is important.
If, according to an advantageous method form, the dough mass is processed with mixing and/or shearing elements for uniform air distribution, a particularly uniform, homogenized air distribution can be achieved in the dough mass, which gives the finished, dried paste or dough product an attractive appearance with a uniform material and optical outward form.
Further dry or liquid components can be supplied as additives to the dough mass during feeding, kneading or in general during processing. For this purpose, e.g. in a conveying or processing zone of the extruder it is possible to supply and in particular inject through openings in a casing wall liquid egg, tomato pulp, spinach, dyes, salt, etc.
In each section of the production process the dough mass is kneaded in order to homogenize it and therefore increase the product quality.
Appropriately air under pressure can be supplied to the dough mass or can be removed under vacuum or underpressure. Thus, a proportion or partial volume of the air or other gaseous substances in the dough mass can be influenced, in order to obtain a clearly defined air volume of the dough mass prior to the finishing of the dough. The injection or suction of air from the dough mass preferably takes place in an extruder gassing or degassing zone and is carried out by means of a pressure apparatus, which can be preferably connected to a decompression zone.
According to an advantageous method step a clearly defined air porosity is produced in the dough mass by a clearly defined pressure setting in the mixing and kneading zone.
In the method according to the invention, a uniform air distribution can be set in the dough mass by a reverse mixing. Part of the dough mass is briefly moved counter to the main feed direction, so that a further homogenization is obtained.
Appropriately there is a planned temperature control in the individual method steps by means of heating and/or cooling the dough mass. Thus, as a function of the temperature of the raw or starting materials such as flour and water, the ambient temperature and the heat produced during dough production, the dough mass can be kept at the desired temperature. The dough mass temperature is maintained below 50xc2x0 C. and preferably at 35 to 40xc2x0 C. This ensures that a temperature is maintained, which is appropriate for the mechanical processing of the dough mass and which must not be exceeded for building up a good gluten framework.
In the method the dough mass is fed and produced in a double shaft extruder with two counter-rotating extruder shafts. This makes it possible to obtain an adequate feed and kneading capacity and an improved air introduction or mixing in the dough mass.
Appropriately the extruder shafts are operated at a speed of approximately 50 r.p.m. This speed leads to a good mixing and kneading result without excessively heating and therefore damaging the dough. Minor variations from this speed are possible, so that when operating below the feed capacity a speed adaptation for a precisely defined air incorporation is obtained.
The method is used with particular advantage if the dough, after finishing and on removing from the extruder is shaped under pressure immediately to a paste product. This leads to a closed process sequence from the supply of the flour and liquid to the removal of the dough to a mould, which has hygienic advantages and also the advantage of continuous, undisturbed operation.
According to the invention, the above object is also achieved by a particular device. The device comprises a casing with at least one driven extruder shaft with a first screw conveyor zone and at least one kneading zone an inlet opening for a milled product such as flour as dry components of the dough, a moisturizing mechanism for the supply of a liquid component to the dry milled product in the vicinity of the first screw conveyor zone and an outlet opening for the prepared dough. As with said device only dry flour or the like is supplied through the inlet opening, due to the lack of moisture, the hygienic conditions at the feed or intake hopper are improved. In addition, the dry flour can be more easily metered and supplied as compared with moist, lumpy flour, which can stick to the surfaces of the hopper.
In the case of the device according to the invention there is a clearly defined mixing of air into the dough mass as a result of operating below the feed capacity. The supply of dry flour or a similar milled product through the hopper and the speed of the screw conveyors are controlled in such a way that the discharge capacity of said screw conveyors (i.e. the possible volume flow) is higher than the milled product quantity actually supplied.
Appropriately the extruder shaft contains a compression zone and a decompression zone, in order to assist a mixing and kneading of the dough mass through changing pressures. In addition, it is possible to provide a suction device for sucking air out of the casing and therefore out of the dough mass in the vicinity of the decompression zone. This makes it possible to set the desired air content in the dough mass.
According to an advantageous embodiment of the extruder the extruder shaft contains a reverse mixing zone following on to the decompression zone. In said reverse mixing zone a brief reverse movement of at least part of the dough mass in opposition to the main feed direction leads to a uniform air distribution in the dough mass.
For this purpose it is advantageous for the extruder shaft to have in the area of the reverse mixing zone reverse mixing elements or a screw conveyor, which has a backward pitch with openings for the dough mass. In order to be able to supply the liquid component of the dough or water, the moisturizing mechanism can have a liquid supply via the casing and/or via the extruder shaft. It is appropriate if the liquid supply has outlet openings for the pressureless entry or discharge nozzles for the injection of liquid under pressure.
The extruder is constructed as a double shaft extruder with two extruder shafts for counter-rotation, which leads to a good mixing of air into the dough mass.
The extruder shafts can be made in one piece or like the casing, can be assembled segmentally from individual functional segments for the different zones.
The device according to the invention can be used with particular advantage if a mold for the dough is located at the extruder outlet. The dough mass can then flow directly and under pressure from the extruder into the mold, where the desired dough or paste product shapes are produced.
Appropriately the mold is made from brass or bronze and has on the mold faces a Teflon coating, so that there is a friction-reducing and virtually adhesion-free surface.
The device can contain a temperature control means with which by the supply or removal of heat or cooling in the individual sections or zones of the extruder shaft, it is possible to set a dough temperature below 50xc2x0 C. For an optimized dough production the dough temperature is kept at approximately 35 to 40xc2x0 C.
For an optical, taste and structural dough improvement a supply device for additives, which is in particular located at a feed zone, is provided, so that it is e.g. possible to supply liquid egg, tomato pulp, spinach, dyes, additional gluten framework constituents, water, salt and other substances.
In a preferred embodiment, each extruder shaft has the following, interconnecting zones: a feed and first conveyor screw zone, a first kneading zone with kneading tools, a second screw conveyor zone, a second kneading zone with kneading tools for homogenizing the dough, a third screw conveyor zone, a compression zone, a decompression zone, a reverse mixing zone for a counter-conveying or counter-feed movement, a kneading zone for fine air distribution and a fourth screw conveyor zone.
The compression zone can be formed by a screw conveyor with increasing screw pitch and/or increasing channel depth and a decompression zone formed by a screw conveyor with decreasing screw pitch and/or decreasing channel depth.